The present invention relates to an improvement in viscose rayon continuous spinning processes.
Viscose rayon continuous spinning processes are known, in which the viscose, extruded from suitable spinnerets into a coagulating bath, undergoes coagulation and drawing in said bath or in successive baths, and thereafter is conveyed to a support and advancing apparatus which causes it to travel in an essentially helical path, viz. a path which is constituted by a series of successive coils whose configuration is not exactly helical but is close to it; the yarn undergoing a series of treatments, while it travels in said path, until it reaches the desired final characteristics. A type of apparatus adapted to impart to the coagulated and drawn yarn a substantially helical path, and to which reference will be made hereinafter, is constituted by a main roller, having a relatively large diameter, and by a series of secondary rollers having much smaller diameters, and having axes which are askew with respect to that of the first one. The secondary rollers are normally called advancing rollers. The main roller is also called the treatment roller because the chemical and thermal treatments occur thereon. Since in devices of this kind, one yarn corresponds to each advancing roller, viz. a plurality of yarns concurrently travel in the apparatus, all the yarns engaging the treatment roller and each yarn separately engaging a distinct advancing roller, reference will be made in describing the present invention to an apparatus having a single advancing roller, and therefore the invention will be described with reference to a single yarn: it being understood, however, that when the invention is carried into practice, a plurality of yarns will generally be treated concurrently and consequently the advancing rollers will be more than one.
The main or treatment roller, and consequently the substantially helical path of the yarn, is divided into several successive zones in the direction of travel of the yarn, or in the longitudinal direction of the treatment roller, a distinct treatment phase corresponding to each of said zones. Said various zones are normally separated by suitable, e.g. mechanical, means, and a very simple separation method consists in providing flanges or pairs of flanges interposed between each zone and those adjacent to it. In describing the invention, reference will be made to a device of this kind, it being understood, however, that the invention is independent of the particular mechanical means with which it is carried into practice.
According to the conventional technique heretofore employed, after the coagulation and drawing of the yarn, a setting by means an acid bath takes place, which is followed in general by a wash, which is followed by desulphuration and generally by a bleaching and finishing treatment, all followed by washes, and finally the yarn is dried.